A new measure on the ballot in November could free up a quarter billion dollars for the city to purchase and renovate small buildings in San Francisco. The measure, Proposition C, would need to win by a two-thirds majority.

If approved, the initiative would be the first since the $310 million bond passed in November 2015 to free up city funds for the creation of permanently affordable housing in the city, according to supporters.

“Proposition C, if it passes, is the only measure on the ballot that will create new affordable housing,” said Fernando Marti, the co-director of the Council of Community Housing Organizations, a non-profit coalition of housing developers and tenants groups.

Proposition C would make $105 million in low-interest loans available for non-profit housing organizations to buy “at-risk” properties in San Francisco with more than three units. Once purchased, they would be brought up to code and turned into permanently affordable housing.

The measure would also make $156 million in loans available to private landlords to make “seismic, fire, health, and safety” upgrades to their units. Those units do not have to affordable and can be market-rate, and would remain with their original owners.

Such upgrades, supporters said, could prevent fires in neighborhoods like the Mission District, which have a preponderance of hundred-year-old buildings with poor wiring.

“The Mission has been devastated by fires,” said Gabriel Medina, the policy manager at the Mission Economic Development Agency, at a press conference held at the corner of Mission and 22nd streets, the site of a building that displaced dozens of tenants when it burned in 2015 and has since been demolished.

Proposition C is a repurposing of funds from a 1992 ballot measure that allocated $350 million for seismic retrofits of brick buildings in the aftermath of the 1989 Loma Prieta earthquake.

Because a majority of brick buildings in the city have been retrofitted and only about $90 million worth of bonds were ever issued, the bulk of the money from the measure can still be used — if voters approve the repurposing in November.

“Over a quarter century ago, you will recall San Francisco had a little crisis — not an affordable housing crisis, but an earthquake crisis,” said Supervisor Aaron Peskin, the sponsor of the ballot measure, at the press conference on Thursday.

“Here we are a quarter century later and $261 of that $350 million remains unspent,” he said.

The money issued by the city would be a low-interest loan that would have to be repaid. Non-profit housing organizations like MEDA or the Community Land Trust would be able to access loans at one-third of the federal funds rate, while private landlords would have loans one percent higher than the federal rate.

The bonds could be issued at a maximum of $35 million per year, under the conditions of the 1992 measure, meaning the $261 million could last eight years. The annual cap could be mixed in any way between the portion for non-profit housing purchase and private safety upgrades, but only $105 million could go towards affordable units and $156 million towards market-rate units.

Marti of the Council of Community Housing Organizations said that for buildings with seven units or more, the cost to buy each building could average $200,000-$250,000 per unit. That means some 420-525 units could be bought total and converted to affordable housing.

The purchase of “small sites” buildings — those between five and 25 units — have run high in the past. The six-unit Pigeon Palace on Folsom Street was one of the first buildings purchased under the city’s Small Sites Program to the tune of $3.3 million — or $600,000 per unit.

Marti said that buildings with fewer than four units are more lucrative for speculators because they can be converted into condos, making them more expensive for non-profit purchase.

Instead, non-profits could focus on buying single-room occupancy hotels and other, larger buildings that would stretch funds to the $250,000 per unit figure, he said.

That per-unit cost does not include the cost of retrofitting the units. Some single-room occupancy hotels, Marti said, would need heavier retrofitting than other buildings with minimal wear and tear, for instance. Non-profit organizations would likely combine the bond money with other state, city, and private funds to purchase and rehab units, he added.

“For us it’s a double whammy,” he said. “We’re buying buildings that have tenants and we’re bringing buildings up to code.”